OBJECTIVE: Variants in ZFYVE19 underlie a disorder characterised by progressive portal fibrosis, portal hypertension and eventual liver decompensation. We aim to create an animal model to elucidate the pathogenic mechanism.
METHODS: Zfyve19 knockout (Zfyve19-/- ) mice were generated and exposed to different liver toxins. Their livers were characterised at the tissue, cellular and molecular levels. Findings were compared with those in wild-type mice and in ZFYVE19-deficient patients. ZFYVE19 knockout and knockdown retinal pigment epithelial-1 cells and mouse embryonic fibroblasts were generated to study cell division and cell death.
RESULTS: The Zfyve19-/- mice were normal overall, particularly with respect to hepatobiliary features. However, when challenged with α-naphthyl isothiocyanate, Zfyve19-/- mice developed changes resembling those in ZFYVE19-deficient patients, including elevated serum liver injury markers, increased numbers of bile duct profiles with abnormal cholangiocyte polarity and biliary fibrosis. Failure of cell division, centriole and cilia abnormalities, and increased cell death were observed in knockdown/knockout cells. Increased cell death and altered mRNA expression of cell death-related signalling pathways was demonstrated in livers from Zfyve19-/- mice and patients. Transforming growth factor-β (TGF-β) and Janus kinase-Signal Transducer and Activator of Transcription 3 (JAK-STAT3) signalling pathways were upregulated in vivo, as were chemokines such as C-X-C motif ligands 1, 10 and 12.
CONCLUSIONS: Our findings demonstrated that ZFYVE19 deficiency is a ciliopathy with novel histological features. Failure of cell division with ciliary abnormalities and cell death activates macrophages and may thus lead to biliary fibrosis via TGF-β pathway in the disease.

In several countries, thyroid dyshormonogenesis is more common than thyroid dysgenesis in patients with congenital hypothyroidism (CH). However, known pathogenic genes are limited to those directly involved in hormone biosynthesis. The aetiology and pathogenesis of thyroid dyshormonogenesis remain unknown in many patients.
To identify additional candidate pathogenetic genes, we performed next-generation sequencing in 538 patients with CH and then confirmed the functions of the identified genes in vitro using HEK293T and Nthy-ori 3.1 cells, and in vivo using zebrafish and mouse model organisms.
We identified one pathogenic MAML2 variant and two pathogenic MAMLD1 variants that downregulated canonical Notch signalling in three patients with CH. Zebrafish and mice treated with N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butylester, a γ-secretase inhibitor exhibited clinical manifestations of hypothyroidism and thyroid dyshormonogenesis. Through organoid culture of primary mouse thyroid cells and transcriptome sequencing, we demonstrated that Notch signalling within thyroid cells directly affects thyroid hormone biosynthesis rather than follicular formation. Additionally, these three variants blocked the expression of genes associated with thyroid hormone biosynthesis, which was restored by HES1 expression. The MAML2 variant exerted a dominant-negative effect on both the canonical pathway and thyroid hormone biosynthesis. MAMLD1 also regulated hormone biosynthesis through the expression of HES3, the target gene of the non-canonical pathway.
This study identified three mastermind-like family gene variants in CH and revealed that both canonical and non-canonical Notch signalling affected thyroid hormone biosynthesis.

Diagnosis of a genetic disease and determination of the causative molecular lesion rely on the availability of the disease-associated pedigrees. Microphthalmia is a congenital eye defect due to an insufficiently developed visual system; its prevalence is 1-3 in 10 000 live births.
We analysed a pedigree exhibiting autosomal dominant inheritance of microphthalmia to determine the genetic lesion; used AlphaFold2 to predict the changes in the protein\'s 3-Dimensional structure; and compared wild-type and variant proteins in cultured cells or Drosophila model was used to explore the cellular or developmental function of the encoded product.
We identified a novel missense variation, F52L, in MAB21L1 that is absent in population databases and present exclusively in the individuals diagnosed with microphthalmia in this pedigree. Common structural changes were predicted for the disease-associated variants clustered at amino acids 49-52, and these variant products were also predominantly trapped in the cytoplasm of cultured human lens epithelia. To recapitulate its dominant effect in development, we expressed the Drosophila homologue corresponding to MAB21L1F52L and caused malformation of sensory organs.
Mutations at the residues 49-52 of MAB21L1 compromise eye development. We recommend including MAB21L1 in the genetic testing panel for congenital eye disorders.

OBJECTIVE: To analyze the clinical phenotype and genetic characteristics of a family with combined oxidative phosphorylation deficiency 1 (COXPD-1).
METHODS: The whole exome sequencing was performed in parents of the proband; and the genetic defects were verified by Sanger sequencing technology in the dried blood spot of the proband, the amniotic fluid sample of the little brother of proband, and the peripheral blood of the parents.
RESULTS: Whole exome sequencing and Sanger validation showed compound heterozygous mutations of GFM1 gene c.688G>A(p.G230S) and c.1576C>T (p.R526X) in both the proband and her little brother, and the c.1576C>T of GFM1 variant was first reported. The two patients were died in early infancy, and presented with metabolic acidosis, high lactic acid, abnormal liver function, feeding difficulties, microcephaly, development retardation and epilepsy.
CONCLUSIONS: GFM1 gene c.688G>A and c.1576C>T compound heterozygous mutations are the cause of this family of COXPD-1.